It worked. Sadly, the EPUB file size increased also. But: you can not have it all
Just a thought: Would it be an idea when selecting a device profile during conversion to mention a short description what it's side effects are? In my case, the current info just stated: "This profile is intended for the Sony PRS line..." I would never have expected that picture resizing was regulated and in which way, let alone what other options more are involved. In this way you are able to experiment and select one which might best suite you.